Class Notes (835,581)
BIOC33H3 (127)
Lecture

# BIOC33/34 Lec 11.docx

10 Pages
101 Views

Department
Biological Sciences
Course
BIOC33H3
Professor
Stephen Reid
Semester
Winter

Description
BIOC34 Lec 11  Pulmonary function tests o Used to diagnose lung diseases o Alveolar ventilation - calculating amount of air going into alveoli  Lung function tests - Spirometry o Done with electronic machines o Standard spirometer used to be a drum in water and person breathes in and out  Drum connected to a pen which makes recordings  Lung volumes o Can sum these lung volumes into lung capacities -give an indication of how well lung is functioning o Tidal volume (Vt) - amount of air on breath by breath basis  On average, Vt is 500ml per breath - average is 12 breaths per minute o If taking a maximal inspiration, amount of air breathed in above and beyond Vt that can maximally be taken in  Inspiratory reserve volume (IRV) o Amount of air that can be expired following normal Vt is referred to as Expiratory reserve volume (ERV) o Exhaling as much as possible, there is still air in lungs  Residual volume (RV) o Can add these volumes to create different lung capacities  Lung capacities o o 1. Inspiratory capacity (IC) = maximum amount of air that we can inspire after a normal expiration  IC = Vt + IRV o 2. Taking maximal inspiration and then breathe out as much as you can to maximum expiratory capacity = vital capacity (VC)  VC = IRV + Vt + ERV  When doing pulmonary function tests, it is called forced vital capacity o 3. Amount of air in lungs after normal tidal expiration = functional residual capacity (FRC)  Expiratory reserve + residual volume = functional residual capacity (FRC = ERV + RV)  In-between inspiration and expiration  Presence of this air exists because lung recoil in and chest recoil out o 4. Total lung capacity (TLC) = sum of everything  (TLC = IRV +Vt + ERV + RV)  Lung volumes and capacities o IC = Vt + IRV o Can measure these variables to see if have lung diseases o Important one = vital capacity (VC)  Obstructive or restrictive lung diseases o Thick lines = where problem exists o Obstructive disease = problem exhaling  Usually some kind of blockage/airway obstruction; something is hindering air going out  Harder to expire  Increase lung resistance (lungs over-inflate) • Asthma, bronchitis, problem with narrowed trachea o Restrictive disease = problem with inhaling  Damage to the lungs, chest wall or pleura  Harder to inspire (inflate lungs)  Decrease lung compliance - cannot inflate properly; lungs have become stiffer • Asbestosis, fibrosis (fibres into lung tissue making them harder)  Pulmonary function tests (forced vital capacity) o When doing these tests, hooked up to a machine and asked to breathe in and breathe out as much as possible and quickly  Forced vital capacity - breathing out as hard and quickly as you can  Vital capacity after first second is a key variable o VC can change or is different in different people o FVC is determined by:  1. Strength of respiratory muscles, chest, diaphragm, etc. will have an effect  more muscular person can push air out much more quickly than someone with weaker lungs and chest muscles  2. Airway resistance - Can change during disease states (asthma, bronchitis)  E.g. narrowed airway due to inflammation or mucous build-up  3. Lung size - can be different or damaged (tuberculosis)  4. Elastic properties of the lung o Can have obstructive disease with restrictive disease origins o Taking a maximal inspiration and breathing out as much as possible  Forced expiratory volume o Forced Expiratory Volume:Amount of forced vital capacity a person can breathe out in a certain amount of time o Can look at forced expiratory volume in seconds after one expires, but usually FEV 1  amount of vital capacity that can be exhaled in 1 second o Both FVC and FEV are going to decrease when there is obstructive and restrictive lung diseases - change in a way that the ratio of the 2 is different depending on type of disease  Pulmonary function tests (FVC and FEV) o Exhale over a 5 second period - take a maximal inspiration in and fill lungs then breathe air out as quickly as possible o Obstructive and restrictive: FVC and FEV1 are low o If ratio between FEV1 to FVC…  Is low (<0.8) , this indicates an obstructive disease  Is normal or slightly higher, this indicates a restrictive lung disease  FVC and FEV o On left = normal  FVC = 5L, FEV1 = 4L  Within first second, 4/5 L are exhaled, therefore ratio = 0.8 o In both  FVC and FRC are lower  Respiratory volume decreases o Obstructive  FEV1 = 1.2 L, FVC = 3.0L  Ratio = 0.4  Lower than normal - indicative of obstructive disease o Restrictive  FEV1 = 2.7 L, FVC = 3 L  Ratio = 0.9  Slightly higher o In pulmonary function tests, want to see if ratios are lower or higher  Inert gas technique ***go over o Can measure lung volume and capacities using inert gas o This is useful for measuring residual volume - what is left in lungs after maximum expiration o Person is hooked up to spirometer but there is 10% helium in the spirometer - person breaths in helium o Come to equilibrium - helium does not get taken into blood; is not soluble  The inert gas technique o Start with helium in spirometer - person is breathing from atmosphere - flip 3-way valve and person breathes helium in o Concentration of helium in lungs becomes equivalent to that in spirometer o This is where dilution comes from - all helium initially present in spirometer is now diluted into gas in the lungs and spirometer  Person is taking air in and out of spirometer  The inert gas technique o Have a spirometer called volume 1 with all the helium in it o After equilibration period, have dilute helium. Concentration is the same throughout the lungs and spirometer (concentration 2) o After dilution, concentration of helium is spread over volume of spirometer and volume of lungs (v2) o Before, concentration of helium in spirometer was entirely in V1 - now diluted concentration (c2) is in lungs and spirometer o V2 = initial volume of spirometer x difference in concentrations divided by C2 o C1 V1 = C2 (V1 + V2) o At end of equilibrium, measure amount
More Less

Related notes for BIOC33H3
Me

OR

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Join to view

OR

By registering, I agree to the Terms and Privacy Policies
Just a few more details

So we can recommend you notes for your school.